Engine Noise From Amp?

I replaced the speakers in my car and kept the OEM amp and now I get engine noise from the rear speakers. When I unplug the amp, and re route the speakers directly off the headunit, the noise is gone. How come my OEM amp is causing this only on aftermarket speakers?

Re: Engine Noise From Amp?

my factory amp doesnt use rcas, just normal wiring. i looked at the car's manual for the wiring diagram. and there isnt a ground wire either. the bolts that hold it down are probably the grounding points. its just weird that only with aftermarket speakers, i get the static. with the factory speakers its fine.

Re: Engine Noise From Amp?

Probably because the stock speakers are pure shit. I'm assuming you are using the stock speaker wire as well? Stock H/U? Best course of action is to upgrade the speaker wiring and get a decent aftermarket H/U and amp. OEM is crap.